Most folding knife structures utilize a partially movable spline along the center of the handle to bias the blade to an open or closed position by sliding contact against the tang of the blade. The required yieldable spring movement of the spine reduces the rigidity of the handle structure, since it limits the handle area across which rigid pins or other connectors can be located. This is a particular problem when handles are constructed of natural materials that expand, contract, or warp unevenly under different atmospheric conditions. Such handles require maximum support by an underlying rigid handle structure.
More refined versions of folding knives have been proposed, typically utilizing mechanically complicated latches to control blade position. Such latches can be manually operated from the exterior of the handle. They usually require manipulation of a protruding button or other mechanism. Such buttons or other mechanisms visually detract from the desired uniform outer appearance of the knife handle. It is also difficult to produce knives with sufficient precision to assure accurate and durable life to such mechanisms.
The present invention arose from an effort to produce a folding knife having a rigid, fixed backstrap along the center of the handle structure, and a releasable positive latch mechanism for the blade, requiring no button or other external mechanism for its operation. The latch mechanism is controlled solely by manual pressure applied to the tang of the knife blade. The latch maintains the blade in a rigid extended position relative to the handle insuring that the blade cannot be accidently folded without specific application of manual pressure at the tang itself.
The latch further maintains the knife blade in a folded position within the handle, acting as a yieldable detent to resist blade movement.